1. Field of the Invention
The present invention relates generally to a zoom lens assembly and more specifically, to a fine adjustment mechanism for linearly adjusting the initial position of a zoom mechanism of the zoom lens assembly.
2. Description of the Related Art
To fit different requirements for different depth of field and different visual field when taking pictures, a zoom mechanism is installed in the lens assembly to provide a continuously adjustable focal length.
However, because the parts of a zoom mechanism have a dimensional error during fabrication or installation, a relatively greater travel path is provided for the zoom mechanism to prevent a zoom failure due to the dimensional error. Although a zoom mechanism has a relatively greater travel path, for example the range between position A and position B in FIG. 1, the needed travel path of the zoom operation is the range between position a and position b in practice. Beyond the range between position a and position b, the lens cannot show the image clearly. Therefore, after assembly of a zoom mechanism, the manufacturer will use a locating ring to support the zoom mechanism, limiting the initial zoom position for the zoom mechanism. However, because the locating ring is directly affixed to the barrel that holds the zoom mechanism, the dimensional error of the related parts must be lowered to assure a satisfactory yield rate after assembly. Further, because the locating ring has the whole surface of one side thereof supporting the zoom mechanism, the parallelism is critical, and therefore the manufacturing of the zoom system is difficult.